研究
行動実験と認知モデリングを用い、人間の社会的意思決定、とくにニ者間の相互作用過程を研究してきました。最近は、ニ者/集団状況において社会情報のタイミングがどのような役割を果たすかを調べています。
Majority rule can help solve difficult tasks even when confident members opt out to serve individual interests
When sharing a common goal, confident and competent members are often motivated to contribute to the group, boosting its decision performance. However, it is unclear whether this process remains effective when members can opt in or out of group decisions and prioritize individual interests. Our laboratory experiment (n = 63) and cognitive modeling showed that at the individual level, confidence, competence, and a preference for risk motivated participants’ opt-out decisions. We then analyzed the group-level accuracy of majority decisions by creating many virtual groups of 25 members resampled from the 63 participants in the experiment. Whereas the majority decisions by voters who preferred to participate in group decision making were inferior to individual decisions by loners who opted out in an easy task, this was reversed in a difficult task. Bootstrap-simulation analyses decomposed these outcomes into the effects of a decrease in group size and a decrease in voters’ accuracy accruing from the opt-in/out mechanism, demonstrating how these effects interacted with task difficulty. Our results suggest that the majority rule still works to tackle challenging problems even when individual interests are emphasized over collective performance, playing a functional as well as a democratic role in consensus decision making under uncertainty.
Behavioral and neuro-cognitive bases for emergence of norms and socially shared realities via dynamic interaction
In the digital era, new socially shared realities and norms emerge rapidly, whether they are beneficial or harmful to our societies. Although these are emerging properties from dynamic interaction, most research has centered on static situations where isolated individuals face extant norms. We investigated how perceptual norms emerge endogenously as shared realities through interaction, using behavioral and fMRI experiments coupled with computational modeling. Social interactions fostered convergence of perceptual responses among people, not only overtly but also at the covert psychophysical level that generates overt responses. Reciprocity played a critical role in increasing the stability (reliability) of the psychophysical function within each individual, modulated by neural activity in the mentalizing network during interaction. These results imply that bilateral influence promotes mutual cognitive anchoring of individual views, producing shared generative models at the collective level that enable endogenous agreement on totally new targets–one of the key functions of social norms.
You watch my back, I’ll watch yours: Emergence of collective risk monitoring through tacit coordination in human social foraging
Predation risk is a significant concern when social animals including humans engage in foraging. When people search for resources together, individuals often find themselves in a producer–scrounger game, in which some individuals bear the cost of risk monitoring while others can free ride on those efforts. A theoretically rational strategy is to mix foraging and risk monitoring randomly with the same probability across all members, but such uncoordinated action often yields inefficiencies of under- or over-supply of risk monitoring in a group. Here, we examined whether people could spontaneously develop a coordinated risk-monitoring system, alternating vigilance and foraging in a pair. Given that human cooperation is vulnerable to fear of exploitation and emotional arousal under risk, we hypothesized that such sources of anxiety would be potential disruptors to coordination. In a laboratory experiment, two participants worked on a “treasure hunt” task simultaneously, in which they chose between low or high vigilance against predators during foraging without verbal communication. If one chose high vigilance with personal cost, it yielded a spillover benefit to the other. Besides behavioral choices, each participant’s physiological arousal (skin conductance response) and cognitive effort (tonic pupil dilation) were measured during the task. Results showed that some pairs were actually able to develop a role-alternating system over time through tacit coordination, but coordinated action was also vulnerable to anxiety and mistrust among participants. Overall, these results imply that, besides the mutual behavioral control that often characterizes repeated interaction, cognitive control of emotional arousal may be a critical psychological factor for the emergence of coordinated cooperation.
